Hard finish for plastering



7 UNITED STATES PATENT OFFI E.

ARTHUR H. \VILLIAMS, OF MANCHESTER, NEW HAMPSHIRE.

HARD FlNlSH FOR PLASTERING.

SPECIFICATION forming part of- Letters Patent No 392.481, dated November 6, 1888.

Application filed April 25, 1888. Serial. NofQTLSlG. (No spreinn-ns.)

To a.Z Z whom it may concern.-

Be itknown that I, ARTHUR H. WILLIAMS, a citizen-f the United States, residing at Manchester, in the county of Hillsborongh and Stateof New Hampshire, have invented certa n new and useful Improvements in llard Finish for Plastering; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

. 'Ijhe invention relates to ahard finish for plas tering, 810.; and it consists in an improved mixture or composition, either colored or plain, for the purpose, and also in the mixture made according to certain proportions, substantially as will be described and claimed.

, My improved hard finish for plastering, &c., has for its main element Franceston n soapstone or its equivalenta soapstone which is obtained at the Francestown quarry, Francestowu, New Hampshire. This soapstone is very different from the ordinary soapstone or talc. Chemical analysis shows that,while talc contains some sixty per cent. of silica, (SiO.

Franccstown soapstone contains but forty-live per cent. Further, it is found that Francestown soapstone contains about ten per cent. of oxide ot'alumininm (AhOQ-a chemical which is totally absent in pure talc. The chemical differences result in making F'ranccstown soapstone a much more valuable and usefnl ingredient in a hard finish such as is contemplated by the present invention, or in a mortar or similar substance, than the common tale, for

certain distinctive qua-lit ies are possessed by the liranccstown soapstone which-peculiarly adapt it for these uses.

.ln addition to Fram-l-slowu soapstone, I cmploy in my composition for a hard finish on plaslcri ng, plnstcr-ol'-.paris, which "is sulphate of lime calcined and pulverized.) Five parts of l rancestown soapstone. are unilcd with one part of plaster-of-paris. 'lhcn a small amount ot acid is added to the mixtu e, alter which the ingredients arcthoroughly nixed together. A ny kind of acid may be used-as, for instance,

dry cream-of-larlur. The object of the acid is to retard the setting of the calcined plaster.

The mixture thus composed is compounded k with lime -puttyin the proportion of three parts of the former to two of the latter.

\Vhcn it is desired to color the mixture, a suitable coloriugqnattcr will be added in sul'licicnt quantity to impart the desired color to the mixture. The plain linish will have a warm pearl-gray col and is not tiresome bul pleasing to the eye.

Owing to the chemical properties of the Fraucestown soapstone, the resulting hard linish of my invention makes asurl'ace which can be washed without injury to the surface or color,onc that is impervious to moisture, gases, germs of disease, amt-stains, and one that can be easily decorated without the use of the customary sizing.

Having thus described my improved hard finish for plastering, what I claim as new, and

lesire to secure by Letters Patent, is-- 1. A hard linish for-plastering composed of plastcr-of-paris, acid, lime-putty, and a soap stone containing some ten per cent. of oxide of aluminium and somel'orty-llvc per cent. of silica, substantially as described.

2. A hard finish for plastering composed of three parts of a mixture of a soapstone containing some ten per cent. of-oxide ol' aluminium and some forty-live percent. of silica, (five parts,) plastcr-ol-paris, (one part.) and a small amount of acid, and two parts of limeputty, substantially as described.

A hard finish consisting of plaster-o1- paris, acid, lime-putty, a cliloring substance, and a soapstone containing ten per cent. of oxidc of aluminium and forty-live per cent. of silica, mixed in the proportions substantially as specified.

In testimony whercol'l. allix my signature in presence oflwo witnesses.

ARTHU R H. WILLIAMS. 

